Commutator electrical machine



y 1954 P. LETRILLIART ETAL 2,683,827

COMMUTATOR ELECTRICAL MACHINE Filed Feb. 11, 1953 Fig.1.

' Fig.2.

Patented July 13, 1954 2,683,827

UNITED STATES PATENT OFFICE 2,683,827 COMMUTATIOR ELECTRICAL MACHINE Pierre Letrilliart and Jean Delastre, Jeumont, France, and Louis Buchet, Binche, Belgium, assignors to Forges & Ateliers de Constructions Electriques de Jeumont, Paris, France, a corporaticn of France Application February 11, 1953, Serial No. 336,406

Claims priority, application France February 20, 1952 Claims. (Cl. 310220) The present invention relates to electrical maported on the hub by spaced arms or spokes 4 chines having commutators. and an annular stack of magnetic sheets 5 hav- In commutator machines, such as traction moing slots in which the elements and l of the tors Operating on -ph s c r e for X rk armature windings or coils are located. The comple, resistance connections have been used be- 5 mutator, mounted on the same shaft, comprises tween the armature coils and the blades or sega hub portion 9, a rim Ii] supported on the hub ments of the commutator, in order to reduce the by spaced radial arms or spokes H and a piushort circuit current in the windings in commurality of commutator segments I? mounted on the tation. In order to elongate the connections rim l0.

and give them the desired resistance values, it In the upper half of Fig. 1, there is shown a has been proposed to let the connections pass resistance connection 8 between a section 1 of through a central bore of the annular armature. the armature winding and a segment 12 of the However, this arrangement gives rise to disturbcommutator. The connection 8 comprises a reing induction phenomena, due to the fact that sistance conductor forming a hairpin 100p 8A, the

the resistance connections pass in the vicinity l5 opposite sides or legs of which are close together of the arms or spokes supporting the armature, and substantially parallel. The loops 8A are disresulting in the production of a magnetic field posed between the successive spokes 4 and loand eddy currents in the spokes, with undesirable cated in the passageways which extend axially reactances and losses. through the armature for the circulation of air It is an object of the present invention to overor other cooling medium. As the instantaneous come these disadvantages by an improved arcurrents flowing in the two legs of the loop are rangement of the resistance connections which always opposite to one another in direction, the virtually eliminates their magnetic effects. A inductive eifect of these currents is practically further object of the invention is to assure efiizero. Hence, each resistance connection, in spite cient ventilation and coolin of the resistance Of its great length, presents practically no inconnections and to provide resistance of the deductance and does not produce any harmful cursired value without undesirable heating. rents in the adjacent metallic portions of the ma- In accordance with the invention, the resistchines such as the hub 2, spokes 4 and rim 3. As

ance connections between the armature windings it is placed in the cooling passage between the and the commutator segments are in the form of spokes, the loop 8A is well cooled. It can have hairpin loops having opposite sides or legs of any desired length, which means that the length the loop close together and disposed in axially can be chosen to give the desired resistance value. eXtending Cooling p ssages provided in the ma- In the lower half of Fig. 1, there is shown anchine. other resistance connection l3 which forms an The objects, nature and advantages of the in- 5 elongated hairpin loop [3A disposed in an axivention will be more fully understood from the ally extending passageway in the commutator befollowing description and claims in conjunction tween successive spokes II. It will be underwith the accompanying drawings which illustrate stood that this loop 13A, from the point of view by way of example preferred embodiments of the of its reactance and cooling, offers the same adinvention. vantages as the loop 8A described above.

In the drawings: In Fig. 2, there are shown the resistance con- Fig. 1 is an axial section of a commutator elecnections l4 having each an elongated hairpin trical machine embodying the invention. loop portion MA disposed in an axially extending Fig. 2 is a partial axial section of a commutator cooling passage in the armature and a second electrical machine illustrating a modification. elongated hairpin loop portion MB disposed in In the accompanying drawings, the armature an aligned cooling passage in the commutator. It windings and resistance connections in accordwill be understood that any or all of the resistance with the invention are shown diagramance connections of the machines may have loop matically, only two connections being shown in portions disposed in axial passageways through Fig. l and in Fig. 2, in order to simplify the drawthe armature, loop portions disposed in axially ings and faciltate an understanding of the invenextending cooling passages throu h the commution. tator, or loop portions disposed both in passages In Figs. 1 and 2, there is shown the rotor of a through the armature and aligned passages motor having a shaft I carrying an armature through the armature. The resistance connecwhich comprises a hub portion 2, a rim 3 suptions are formed of suitable wires, bars, rods, ribbone, etc. having the desired values and may be either straight or twisted. While preferred embodiments of the invention have been shown, by way of example, in the drawings, it will be understood that the invention is not limited to the specific examples shown and described.

What we claim and desire to secure by Letters Patent is:

1. In a commutator electrical machine, a rotor comprising an armature and a commutator having a plurality of segments, said rotor having cooling passages extending therethrough in an axial direction, windings on said armature and connections between the armature windings and individual commutator segments, said connections comprising resistance conductors in the form of elongated hairpin loops disposed in said passages approximately parallel to the axis of the rotor and having opposite legs of said loops close together.

2. In a commutator electrical machine, a commutator having a plurality of segments, an armature core having a plurality of cooling passages extending therethrough in an axial direction, windings on said armature core and connections between said windings and individual commutator segments, said connections comprising resistance conductors in the form of elongated hairpin loops disposed in said passages approximately parallel to the axis of the commutator and having opposite legs of said loops close together.

3. In a commutator electrical machine, a commutator having a plurality of segments and a plurality of cooling passages extending through the commutator in an axial direction, an armature core adjacent said commutator, windings on said armature core and connections between said windings and individual commutator segments, said connections comprising resistance conductors in the form of elongated hairpin loops disposed in said passages approximately parallel to the axis of the commutator and having opposite legs or said loops close together.

l. In a commutator electrical machine, a commutator having a plurality of segments and a plurality of cooling passages extending axially through the commutator in an axial direction, an armature core adjacent the commutator and having a plurality of cooling passages extending in an axial direction and communicating with said passages in the commutator, windings on said armature core and connections between said windings and individual commutator segments, said connections comprising resistance conductors in the form of elongated hairpin loops disposed in said passages approximately parallel to the axis of the commutator and armature and having opposite legs of said, loops close together.

5. In an alternating current machine of the type having axially extending cooling air passages, a commutator and resistive connections between said commutator and the armature windings, a structure for eliminating induction phenomena produced by said connections, wherein said connections are in the form of narrow hairpin loops disposed in said cooling passages.

References Cited in the file or" this patent UNITED STATES PATENTS Number Name Date 780,047 Lamme Jan. 17, 1905 FOREIGN PATENTS Number Country Date 535,52e France Jan. 26, 1922 

